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<?php
/**
* @copyright Copyright (c) 2016 Lukas Reschke <lukas@statuscode.ch>
*
* @author Lukas Reschke <lukas@statuscode.ch>
*
* @license GNU AGPL version 3 or any later version
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
namespace OC\Security\Bruteforce;
use OCP\AppFramework\Utility\ITimeFactory;
use OCP\IConfig;
use OCP\IDBConnection;
use OCP\ILogger;
/**
* Class Throttler implements the bruteforce protection for security actions in
* Nextcloud.
*
* It is working by logging invalid login attempts to the database and slowing
* down all login attempts from the same subnet. The max delay is 30 seconds and
* the starting delay are 200 milliseconds. (after the first failed login)
*
* This is based on Paragonie's AirBrake for Airship CMS. You can find the original
* code at https://github.com/paragonie/airship/blob/7e5bad7e3c0fbbf324c11f963fd1f80e59762606/src/Engine/Security/AirBrake.php
*
* @package OC\Security\Bruteforce
*/
class Throttler {
const LOGIN_ACTION = 'login';
/** @var IDBConnection */
private $db;
/** @var ITimeFactory */
private $timeFactory;
/** @var ILogger */
private $logger;
/** @var IConfig */
private $config;
/**
* @param IDBConnection $db
* @param ITimeFactory $timeFactory
* @param ILogger $logger
* @param IConfig $config
*/
public function __construct(IDBConnection $db,
ITimeFactory $timeFactory,
ILogger $logger,
IConfig $config) {
$this->db = $db;
$this->timeFactory = $timeFactory;
$this->logger = $logger;
$this->config = $config;
}
/**
* Convert a number of seconds into the appropriate DateInterval
*
* @param int $expire
* @return \DateInterval
*/
private function getCutoff($expire) {
$d1 = new \DateTime();
$d2 = clone $d1;
$d2->sub(new \DateInterval('PT' . $expire . 'S'));
return $d2->diff($d1);
}
/**
* Return the given subnet for an IPv4 address and mask bits
*
* @param string $ip
* @param int $maskBits
* @return string
*/
private function getIPv4Subnet($ip,
$maskBits = 32) {
$binary = \inet_pton($ip);
for ($i = 32; $i > $maskBits; $i -= 8) {
$j = \intdiv($i, 8) - 1;
$k = (int) \min(8, $i - $maskBits);
$mask = (0xff - ((pow(2, $k)) - 1));
$int = \unpack('C', $binary[$j]);
$binary[$j] = \pack('C', $int[1] & $mask);
}
return \inet_ntop($binary).'/'.$maskBits;
}
/**
* Return the given subnet for an IPv6 address and mask bits
*
* @param string $ip
* @param int $maskBits
* @return string
*/
private function getIPv6Subnet($ip, $maskBits = 48) {
$binary = \inet_pton($ip);
for ($i = 128; $i > $maskBits; $i -= 8) {
$j = \intdiv($i, 8) - 1;
$k = (int) \min(8, $i - $maskBits);
$mask = (0xff - ((pow(2, $k)) - 1));
$int = \unpack('C', $binary[$j]);
$binary[$j] = \pack('C', $int[1] & $mask);
}
return \inet_ntop($binary).'/'.$maskBits;
}
/**
* Return the given subnet for an IP and the configured mask bits
*
* Determine if the IP is an IPv4 or IPv6 address, then pass to the correct
* method for handling that specific type.
*
* @param string $ip
* @return string
*/
private function getSubnet($ip) {
if (\preg_match('/^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$/', $ip)) {
return $this->getIPv4Subnet(
$ip,
32
);
}
return $this->getIPv6Subnet(
$ip,
128
);
}
/**
* Register a failed attempt to bruteforce a security control
*
* @param string $action
* @param string $ip
* @param array $metadata Optional metadata logged to the database
*/
public function registerAttempt($action,
$ip,
array $metadata = []) {
// No need to log if the bruteforce protection is disabled
if($this->config->getSystemValue('auth.bruteforce.protection.enabled', true) === false) {
return;
}
$values = [
'action' => $action,
'occurred' => $this->timeFactory->getTime(),
'ip' => $ip,
'subnet' => $this->getSubnet($ip),
'metadata' => json_encode($metadata),
];
$this->logger->notice(
sprintf(
'Bruteforce attempt from "%s" detected for action "%s".',
$ip,
$action
),
[
'app' => 'core',
]
);
$qb = $this->db->getQueryBuilder();
$qb->insert('bruteforce_attempts');
foreach($values as $column => $value) {
$qb->setValue($column, $qb->createNamedParameter($value));
}
$qb->execute();
}
/**
* Get the throttling delay (in milliseconds)
*
* @param string $ip
* @return int
*/
public function getDelay($ip) {
$cutoffTime = (new \DateTime())
->sub($this->getCutoff(43200))
->getTimestamp();
$qb = $this->db->getQueryBuilder();
$qb->select('*')
->from('bruteforce_attempts')
->where($qb->expr()->gt('occurred', $qb->createNamedParameter($cutoffTime)))
->andWhere($qb->expr()->eq('subnet', $qb->createNamedParameter($this->getSubnet($ip))));
$attempts = count($qb->execute()->fetchAll());
if ($attempts === 0) {
return 0;
}
$maxDelay = 30;
$firstDelay = 0.1;
if ($attempts > (8 * PHP_INT_SIZE - 1)) {
// Don't ever overflow. Just assume the maxDelay time:s
$firstDelay = $maxDelay;
} else {
$firstDelay *= pow(2, $attempts);
if ($firstDelay > $maxDelay) {
$firstDelay = $maxDelay;
}
}
return (int) \ceil($firstDelay * 1000);
}
/**
* Will sleep for the defined amount of time
*
* @param string $ip
*/
public function sleepDelay($ip) {
usleep($this->getDelay($ip) * 1000);
}
}
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